This invention relates to a combination seal and tentering means for an electrolysis cell.
Membrane-type electrolysis cells, i.e., electrolysis cells employing membranes interposed between a pair of adjacent electrode frames, typically use a separate and independent seal means, for example, a gasket, interposed between the membrane and an electrode frame member to provide a gas and electrolyte tight seal for the cell.
In addition to a seal means, membrane type electrolysis cells typically use a separate and independent tentering device to planarly dispose the membrane between at least two flat surface, parallel flanges of opposing anodes and cathodes. There are several problems associated with a non-planar membrane, or a wrinkled membrane, installed between electrode frames of an electrolysis cell during operation of the cell. For example, a wrinkled membrane can reduce the circulation of electrolyte or can trap gas bubbles between the electrode and the membrane face, resulting in a nonuniform increase of the resistivity of the electrolyte solution in ther interelectrode space with the nonuniform current distribution in the vertical direction. This leads to an increase in current consumption and relatively higher costs in operating a cell. This can also cause leaks in the membrane which can damage the external structure of the cell and loss of cell efficieny.
The method of tentering the membranes and sealing the membrane-type cells becomes increasingly important in flat plate-type or filter press-type electrolysis cells where several repeating units of membranes and electrode frames are used. Conventional methods for tentering the membrane and sealing the cell have included using a separate gasket and tentering device. One method of tentering the membrane involves holding the membrane by hand between cell frames and stretching the membrane as the cell frames are compressed together. The cell gaskets in this instance are glued to one of the electrode frames. In another method, the cell frames, membranes and gaskets are assembled in the horizontal position to ensure a planar placement of the membrane and gaskets, and thereafter standing the assembled cell in the upright position for operation. Still another method, the membrane and gasket are glued to the cathode or anode frame prior to assembling the elements of the cell together.
The above approaches are unsatisfactory as they present time consuming, complex procedures, costly equipment and safety hazards to personnel. It is desired to provide a means suitable for sealing an electrolysis cell and tentering an electrolysis separator to reduce the complexity of assembling the elements of an electrolysis cell.